Fuse cartridge



Aug 23, 1932. L. s. WALDRON ET AL 8 5 FUSE CARTRIDGE Filed Aug. 2, 1930 I a with the caps removed;

Patented Aug. 23, 1932 UNI D, STATES PATENT? OFFICE LEWIS S. WALDRQNAND TRENT B. TERRY, OF CHABLOTTESVILLE, VIRGINIA FUSE CARTRIDGE Application filed August 2, 1930. Serial No. 472,674.

This invention'relates to fusecartridges and more particularly to fuse cartridges of the renewable or refillable type.

It is a general object of the present lnvention to provide a novel and improved refillable fuse cartridge. 1

More particularlyit "is an object of the invention to provide a fuse cartridge having removable caps or end members which are normally locked and retained in position'by continuous spring pressure, whereby dislodgement of the cap and separation of the parts by vibration is effectively prevented.

:One of theimportant'features of the In- 'vention resides. in providing caps and coupling members on the tube with complementary; parts forming bayonet o nts locked against any except: intentional removal,

,Another feature of the invention resides in the manner of providing'electrical contact between the fuse element and the'caps. wherein spring clips, slidable over the ends of the fuse element are arranged one in each cap.

Still another feature of the invention resides in the provision of separate end members for reenforcing the insulating tube and providing the necessary parts of the interlocking joint between the cap and tube. t Other and further featuresv and objects of the invention will be more apparent to those skilled in the art upon a consideration of the accompanying drawing and following specification wherein is disclosed a single exemplary embodiment of theinvention with the understanding, however, that such changes maybe made therein as fall within the scope of the appended-claims without departing from the spirit of the invention.

In said drawing: 1 I i Figural is a longitudinal central sect-ion throng a fuse cartridge constructed according to the present invention; j 1

Figure 2 is an elevation of the cartridge 'Figurei3 is a central longitudinal section of one end of the fuse cartridge, the view being taken at right angles to that of Figure 1; Figure 4 is a view in longitudinal section I ofacap memberseparate fromsthe tube; and

Figure 5 is a view looking into the end of a cap member.

Renewable fuses, i. e., fuses wherein the fuse element, and its mounting, if one be used, can be removed from the cartridge or container and replaced by a perfect one or one of a different capacity, are well known. Difliculty, however, has been experienced in forms heretofore used, both in making satisfactory contact between the caps or end members of the tube and the fuse element, and in retaining these caps in position against unintentional displacement. The caps, of course, are the terminals of the fuse and fit in suitable clips for making connection with the fused circuit. The cap must have well nigh perfect contact with the fuse element for otherwise the contact resistance will cause sufficient localized heating to meltthe readily fusible material. The present invention contemplates improvements both in the method of connecting the fuse element to the cap and in securing the cap to the tube.

Referring now to the drawing there is shown at 10 the usual enclosing tube of insulating material made for instance of fibre, bakelite or the like which houses thefuse element proper indicated by the reference character 11. This fuse element comprises the fiat strip l2-of insulating material support ing the fusible link 13. In the present in-' stance the link 13 is a narrowed portion of the terminal members 14, formed of suitable fusible metal of about the same width'as the insulating strip 12 whichloosely fits the walls of the tube. The ends of the terminal members 14 are bent around the ends of the strip 12 and folded down on the opposite side as shown at 15 so that both sides of the ends of the insulating strip are covered by the fuse metal; In order toreduce arcing and other difficulties experienced in fuses, one-half of the length of the fuse member is on one side of the strip and the other half on the other side, the center of the link passingthrough the hole 16 therein. The slits 17 radiate from the opening 16 to permit the insertion of one of theend members 14 during assembly of the fuse on the strip. I i 1 The fuse element assembly is slightly longer than the total length of the tube 10 and is secure both electrically and mechanically to the caps 20 by means of spring clips 21. These clips each comprise a strip of spring meta having its central portion 22 riveted to tl e base 23 of the cap as at 2% and bent to provide spaced parallel sides or arms 25 normally closer together than the thickness of the two parts of the fuse metal and the included strip. The ends of the arms 25 are flared at 26 to provide an easy entrance for the fuse between the arms.

Each cap includes the circular base 23 and the tubular portion 28 either formed integral or of suitably connected parts. The tubular portions 28 are adapted to pass over the ends of the tube and to be secured thereto by mech anism now about to be described.

For purposes for reenforcing the ends of the cartridge tube, which may be used over and over again, it is provided with metal ferrules 30 of substantially the same diameter as the tube and having threaded engagement as at 31 with the reduced ends of the tube. These ferrules are t ghtly screwed on the tube at the two ends thereof and have their outer ends flush with the ends of the tube and their inner ends 32 abutting the shoulders 33 on the tube. Each ferrule is provi ed with a plurality of longitudinal grooves or channels 35. Preferably four s r channels equally spaced about the periuhery are provided. Each of these channels is connected by means of a crossover groove 36 with a parallel channel 37 the outer end of which is closed, thus forming one of the complementary members of a bayonet oint.

The other member of the bayonet joint is formed by having a stud or projection 38 on the sleeve 28 of the cap.

the inner wall or On each cap there are the same number of these projections as there are grooves in the ferrule so that the cap can be positioned by telescoping it over the ferrule and sliding the projections 38 through the grooves 35 until they reach a position where by partial rot tion of the cap the projections pass through the crossovers 36 and are received in the short longitudinal grooves 37 To lock the caps in position each 's provided with a coil spring iO therein loosely surrounding the fuse clip and pressing the annular washer 4-1 toward the open end of the ca l l hen the cap removed from the tube the washer s nrevented from coming out of position by t1 tuds 38 against whiclrit is firmly held by the "pring. hen the can applied to the end .f bears on the end oft ie p is the tube the wa her 4O ferrule and comp the spr ng so that after the studs 38 hav -n rotatel hrouejh the crossovers ar drawn into the closed outer en grooves 37 and held there by spring pressure againstany accidental or unintentional displacement.

The springs which hold the caps in position insure rigid connections between the caps and tube and prevent such movement from vibration or the like as mightendager the quality of contact between the fuse element and cli s.

{Vhen assemblying the. fuse cartridge and fuse element is first inserted into the tube and the caps one by one placed in position by first forcing the clip over the end of the fuse elementand then telescoping the cap over the tube and continuing with the movement necessary to lock the bayonet joint. The slight relative movement between the cap and tube may twist the fuse assembly slightly when applying the second cap but it is of sufficient resiliency to permit this twisting through the small angle necessary for make ing the connection.

The construction just described is extremely simple in manufacture and operation and has been found in practice to be much more effective than the forms heretofore used.

Having thus described the invention, what is claimed as new and desired to be secured secured to said cap, projecting through said spring and adapted to resiliently engage the fuse element.

2. In a renewable fuse cartridge, in combination, a. tube of insulating material adapted to house a. fuse element, a metal reenfoming ferrule secured to one end of said tube, a. metal terminalcap adapted to telescope over said tube end, means forming an interlocking joint between the said cap and ferrule, a. spring in said cap to maintain said joint against accidental unlocking and a spring clip secured to said cap, projecting through said spring and adapted to resiliently engage the fuse element.

3. In a fuse cartridge, in combination, a. tube of insulating material, a replaceable fuse element in said tube comprising a strip of insulating material to loosely fit the bore of the tube and a fusible member in contact with one face of the strip at eachend thereof; a. reenforcing ring on each end of the tube, a terminal cap for each end of said tube, interlocking means on the caps and rings, a spring on each cap to secure it in interlocked relation with its ring and a spring clip in each cap to resiliently clamp the strip and fusible element just prior to and after the cap is interlocked with the ring.

4. In a renewable fuse cartridge, in combination, a tube of insulating material, adapted to house a fuse element, a metal terminal cap adapted to telescope over the end of said tube, means forming an interlocking joint between said cap and tube, an annular washer against the action of said spring, and a sprin in said cap arranged to bear against sai washer to force the same against the end of said tube, and a spring clip secured to said cap, projecting through said spring and washer and adapted to resiliently engage'the fuse element. 7 I

5. A terminal cap for a fuse cartridge having, in combination, a tubular portion and a base, an annular washer slidably mounted in said tubular portion, a coiled spring also mounted in said tubular ortion and arranged between said base and said annular washer and pressing against the latter, means for retaining said washer in said tubular. portion against the action of said spring, and a spring clip secured to said base and projecting through said coiled spring and said washer.

In testimony whereof we hereunto aflix our signatures.

LEWIS S. WALDRON. TRENT B. TERRY; 

